Electrophysiological experiments using intracellular recording and extracellular iontophoretic techniques have been performed both on mouse spinal neurons grown in tissue culture and on molluscan central neurons. The research has focused on two questions: 1) what roles do amino acids and peptides play in neuronal function? and 2) what are the membrane mechanisms of action of clinically important anticonvulsants, anesthetics and convulsants? We have been able to describe a variety of operationally distinct effects on opiate peptides, including a new class of action defined as neuromodulation. Using a newly envolved statistical analysis of membrane events ("noise analysis") we have been able to show that 1) putative inhibitory amino acid transmitters activate channels of different properties and 2) clinically important drugs can modulate these properties. The resolution of these results eclipses all previous efforts by this or any other laboratory and emphasizes the usefulness of cultured central neurons as a preparation to ask increasingly rigorous questions regarding CNS functioning.